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B K Jha - One of the best experts on this subject based on the ideXlab platform.

  • processing of low carbon deep drawing steel with high plastic anisotropy using two stage batch annealing cycle
    Journal of Materials Engineering and Performance, 2021
    Co-Authors: A Deva, Pratiksha Pandey, M Alam, Biraj Kumar Sahoo, Ravi B Kumar, Sandip Ghosh Chowdhury, B K Jha
    Abstract:

    Anisotropy in texture determines capacity of the steel to achieve maximum plastic flow in the plane of the sheet and maximum resistance to flow in a direction perpendicular to the sheet. Present work has been carried out to explore the potential of maximizing plastic anisotropy (r(m)) value in extra deep-drawing steel. Industrial heat was made with low carbon (0.03 wt.%), low manganese (0.15 wt.%), and low sulfur (0.007 wt.%) levels. Continuously cast slabs were hot-rolled and then cold-rolled to 1 mm thickness. The cold-rolled sheets were subsequently subjected to annealing in an annealing simulator furnace adopting specially designed two-stage batch annealing cycle. In batch-annealed steel samples, grains were found to be recrystallized and had undergone grain growth preferentially along the longitudinal direction with strong gamma fiber, comparable to that of Interstitial Free steel. Excellent combination of strength and forming properties, in terms of yield strength 190 MPa, ultimate tensile strength 290 MPa, and total elongation 45%, YS/UTS: - 0.66 with very high plastic anisotropy (r(m)): 2.45, could be achieved. Properties achieved have been correlated with the alloy chemistry, processing path history, percentage reduction, two-stage batch annealing cycle and the resultant grain size, microstructure and texture.

  • effect of b n ratio on plastic anisotropy behaviour in low carbon aluminium killed steel
    Materials Science and Technology, 2008
    Co-Authors: A Deva, B K Jha
    Abstract:

    It is well known that dissolved nitrogen in ferrite seriously impairs the formability of hot rolled unalloyed steel. Boron being a strong nitride former, combines aggressively with dissolved nitrogen in steel, and thereby improves the forming properties. Further, atomic ratio of boron to nitrogen (B/N) plays an important role in influencing the microstructure and properties of low carbon steel. Whenever excess boron is present in solution in austenite, it segregates to the c grain boundary, thus inhibiting the transformation of austenite to ferrite, and resulting in increase in hardenability of steel. Although plenty of works have been carried out on the effect of boron on properties of hot rolled steels, limited literature is available on its effect in cold rolled formable grades particularly when carbon is in the range 0?03–0?06 wt-%. The present paper discusses the effect of B/N atomic ratio on the forming properties in general and plastic anisotropy ratio rm in particular, in low carbon aluminium killed batch annealed steel. The present study has been carried out on the industrially produced low carbon (0?04–0?06 wt-%) steel with varying B/N atomic ratio. The chemical composition of steels used for the present study is shown in Table 1. Steel A is the typical chemistry used for producing extra deep drawing steel. All the steels were continuously cast to 210 mm thick slabs and were hot rolled to 2?8 mm thickness. The hot rolled bands were finish rolled at 880i10uC and coiled at 620i10uC. As lower coiling temperature (,600uC) results in higher rm values in batch annealed aluminium killed steel, some coils were coiled at 540uC also. Hot rolled coils were cold reduced to 1 mm thickness. The cold rolled coils were annealed with shorter and longer annealing cycles as schematically shown in Fig. 1. Conventionally shorter annealing cycle is practiced for normal cold rolled steel whereas longer annealing cycle is used for extra deep drawing grade. Table 2 shows the mechanical properties of steels with varying B/N ratio processed under different annealing cycles. Properties of boron added steel has shown a significant improvement compared to steel without boron in terms of lower yield strength and higher elongation. In spite of being subjected to similar hot rolling conditions and annealing cycle parameters, lower YS (242 MPa), lower UTS (360 MPa) and higher elongation has been obtained in boron added steel B1 as compared to boron free steel A. It can be attributed to the reduced solute nitrogen and carbon contents in Steel. As expected, increasing the annealing time has led to lowering the strength values and increasing elongation further. As the tensile properties alone does not depict the forming behaviour of cold rolled steel completely, plastic anisotropy ratio r, which is a good measure of deep drawability of steel, has been assessed. A mean value rm is defined as rm5(r0z2r45zr90)/4, where subscripts refer to the angles of tensile tests to the rolling direction. Figure 2 shows the effect of B/N ratio on rm for the steels (with and without boron) annealed with longer cycle. Steel with B/N ratio of 0?8 (steel C) shows lower value of rm (1?12) as compared to rm value of 1?66 in steel with B/N ratio of 0?3 (steel B2) processed under identical conditions of hot/cold rolling and annealing. The rm value of steel A, subjected to coiling temperature of 540uC and longer annealing cycle, has also been compared to steel B3 to assess the effect of boron. rm for both the steel were found to be nearly same (Fig. 2) with value of 1?76 for steel A and value of 1?74 for steel B3. The results show that lower value of B/N ratio does not affect rm adversely. It can be explained in terms of availability of nitrogen for AlN precipitation in steel during batch annealing. Depending on the Al, B and N concentration in steel, the range of temperature at which AlN and BN precipitate coincide in general. However, Ohmari and Yamanaka have reported that BN will form first compared to AlN due to higher diffusivity of boron. In the present study also, it appears that most of nitrogen has been combined by boron before precipitation of AlN in the hot rolled stage, which in turn has resulted in lower availability of nitrogen in solution depending on B/N atomic ratio for combining with aluminium during batch annealing. It is well known that there is strong influence of aluminium nitride during batch annealing of aluminium killed steel. High rm values are produced by textures containing a high proportion of grains with (111) planes and low proportion of (100) planes parallel to the sheet surface. The aluminium nitrides lead to enhancement of the (111) texture components and a concurrent reduction of the (100) components. While developing the desirable texture, aluminium nitrides also help at the same time in formation of a pancake grain structure which results in better rm value in steel. This emphasises the Research and Development Centre for Iron and Steel, Steel authority of India Limited, Ranchi, 834002, India

R K Ray - One of the best experts on this subject based on the ideXlab platform.

Purushothaman Damodaran - One of the best experts on this subject based on the ideXlab platform.

  • a simulated annealing algorithm to minimize makespan of parallel batch processing machines with unequal job ready times
    Expert Systems With Applications, 2012
    Co-Authors: Purushothaman Damodaran, Mario C Velezgallego
    Abstract:

    A simulated annealing (SA) algorithm to minimize the makespan on a group of identical batch processing machines arranged in parallel is presented. We consider the case where each job has an arbitrary processing time, non-identical size, and non-zero ready time. Each machine can process simultaneously several jobs as a batch as long as the machine capacity is not exceeded. The batch processing time is equal to the largest processing time among those jobs in the batch. Similarly, the batch ready time is equal to the largest ready time among all the jobs in the batch. Random instances were used to compare the results of the SA approach against a lower bound, a mathematical model, and two heuristics published in the literature: the Modified Delay (MD) heuristic and a Greedy Randomized Adaptive Search Procedure (GRASP). Computational experiments showed that the SA approach is comparable to GRASP with respect to solution quality, and less computationally costly. Both SA and GRASP comfortably outperformed the MD heuristic.

  • minimizing makespan on a batch processing machine with non identical job sizes using genetic algorithms
    International Journal of Production Economics, 2006
    Co-Authors: Purushothaman Damodaran, Praveen Kumar Manjeshwar, K Srihari
    Abstract:

    Abstract This paper aims at minimizing the makespan for a batch-processing machine. The processing times and the sizes of the jobs are known. The machine can process a batch as long as its capacity is not exceeded. The processing time of a batch is the longest processing time of all the jobs in that batch. This problem is NP-hard and hence a genetic algorithm (GA) approach is proposed. Random instances were used to test the effectiveness of the proposed approach. The results obtained from GA were compared with a simulated annealing approach and a commercial solver. The results indicate that the GA was able to arrive at better makespan with shorter run times.

  • minimizing makespan on parallel batch processing machines
    International Journal of Production Research, 2004
    Co-Authors: Ping-yu Chang, Purushothaman Damodaran, Sharif H Melouk
    Abstract:

    A simulated annealing approach to minimize makespan for identical parallel batch-processing machines is presented. Each job has a corresponding processing time and size. The machine can process the jobs in batches as long as the total size of all the jobs in a batch does not exceed the machine capacity. The processing time of a batch is equal to the longest processing time among all the jobs in the batch. Random instances were generated to test the approach with respect to solution quality and run time. The results of the simulated annealing approach were compared with CPLEX. The approach outperforms CPLEX on most of the instances.

  • minimizing makespan for single machine batch processing with non identical job sizes using simulated annealing
    International Journal of Production Economics, 2004
    Co-Authors: Sharif H Melouk, Purushothaman Damodaran, Ping-yu Chang
    Abstract:

    Abstract This research proposes a simulated annealing (SA) approach to minimize makespan for a single batch-processing machine. Each job has a corresponding processing time and size. The machine can process the jobs in batches as long as the machine capacity is not exceeded. The processing time of a batch is equal to the longest processing time among all jobs in the batch. Random instances were generated to test our approach with respect to solution quality and run time. The results of the SA approach were compared to CPLEX. Our approach outperforms CPLEX on all the instances.

Wenge Zheng - One of the best experts on this subject based on the ideXlab platform.

  • verification of the competitive effect between heterogeneous and gas diffusion induced cell nucleation in determining the cell structure in polystyrene poly methyl methacrylate blends via structural evolution driven by phase separation
    Industrial & Engineering Chemistry Research, 2019
    Co-Authors: Wei Liu, Yongyan Pang, Bingjie Guo, Kangpei Qin, Xia Dong, Dujin Wang, Wenge Zheng
    Abstract:

    The objective of the present work is to verify the competitive effect between the heterogeneous and gas-diffusion cell nucleation in foaming of polystyrene/poly(methyl methacrylate) (PS/PMMA) blends with PS or PMMA as the dispersed phase after structural evolution driven by phase separation. Four PS/PMMA blends were thermally annealed for various times. Scanning electron microscopy (SEM) was employed to study the phase morphology. The domain size and domain density were thus obtained, and the interface area was then calculated. The samples were foamed via a batch foaming process, and SEM was used to study the cell structure. It was found that with thermal annealing, the phase domain size was increased, the domain density was decreased, and the interface area was decreased. For PS20/PMMA80 and PS30/PMMA70, the cell size was increased and cell density was decreased, while for PS80/PMMA20 and PS70/PMMA30, the cell size was decreased and cell density was increased. The expansion ratio was decreased for all of...

A Deva - One of the best experts on this subject based on the ideXlab platform.

  • processing of low carbon deep drawing steel with high plastic anisotropy using two stage batch annealing cycle
    Journal of Materials Engineering and Performance, 2021
    Co-Authors: A Deva, Pratiksha Pandey, M Alam, Biraj Kumar Sahoo, Ravi B Kumar, Sandip Ghosh Chowdhury, B K Jha
    Abstract:

    Anisotropy in texture determines capacity of the steel to achieve maximum plastic flow in the plane of the sheet and maximum resistance to flow in a direction perpendicular to the sheet. Present work has been carried out to explore the potential of maximizing plastic anisotropy (r(m)) value in extra deep-drawing steel. Industrial heat was made with low carbon (0.03 wt.%), low manganese (0.15 wt.%), and low sulfur (0.007 wt.%) levels. Continuously cast slabs were hot-rolled and then cold-rolled to 1 mm thickness. The cold-rolled sheets were subsequently subjected to annealing in an annealing simulator furnace adopting specially designed two-stage batch annealing cycle. In batch-annealed steel samples, grains were found to be recrystallized and had undergone grain growth preferentially along the longitudinal direction with strong gamma fiber, comparable to that of Interstitial Free steel. Excellent combination of strength and forming properties, in terms of yield strength 190 MPa, ultimate tensile strength 290 MPa, and total elongation 45%, YS/UTS: - 0.66 with very high plastic anisotropy (r(m)): 2.45, could be achieved. Properties achieved have been correlated with the alloy chemistry, processing path history, percentage reduction, two-stage batch annealing cycle and the resultant grain size, microstructure and texture.

  • effect of b n ratio on plastic anisotropy behaviour in low carbon aluminium killed steel
    Materials Science and Technology, 2008
    Co-Authors: A Deva, B K Jha
    Abstract:

    It is well known that dissolved nitrogen in ferrite seriously impairs the formability of hot rolled unalloyed steel. Boron being a strong nitride former, combines aggressively with dissolved nitrogen in steel, and thereby improves the forming properties. Further, atomic ratio of boron to nitrogen (B/N) plays an important role in influencing the microstructure and properties of low carbon steel. Whenever excess boron is present in solution in austenite, it segregates to the c grain boundary, thus inhibiting the transformation of austenite to ferrite, and resulting in increase in hardenability of steel. Although plenty of works have been carried out on the effect of boron on properties of hot rolled steels, limited literature is available on its effect in cold rolled formable grades particularly when carbon is in the range 0?03–0?06 wt-%. The present paper discusses the effect of B/N atomic ratio on the forming properties in general and plastic anisotropy ratio rm in particular, in low carbon aluminium killed batch annealed steel. The present study has been carried out on the industrially produced low carbon (0?04–0?06 wt-%) steel with varying B/N atomic ratio. The chemical composition of steels used for the present study is shown in Table 1. Steel A is the typical chemistry used for producing extra deep drawing steel. All the steels were continuously cast to 210 mm thick slabs and were hot rolled to 2?8 mm thickness. The hot rolled bands were finish rolled at 880i10uC and coiled at 620i10uC. As lower coiling temperature (,600uC) results in higher rm values in batch annealed aluminium killed steel, some coils were coiled at 540uC also. Hot rolled coils were cold reduced to 1 mm thickness. The cold rolled coils were annealed with shorter and longer annealing cycles as schematically shown in Fig. 1. Conventionally shorter annealing cycle is practiced for normal cold rolled steel whereas longer annealing cycle is used for extra deep drawing grade. Table 2 shows the mechanical properties of steels with varying B/N ratio processed under different annealing cycles. Properties of boron added steel has shown a significant improvement compared to steel without boron in terms of lower yield strength and higher elongation. In spite of being subjected to similar hot rolling conditions and annealing cycle parameters, lower YS (242 MPa), lower UTS (360 MPa) and higher elongation has been obtained in boron added steel B1 as compared to boron free steel A. It can be attributed to the reduced solute nitrogen and carbon contents in Steel. As expected, increasing the annealing time has led to lowering the strength values and increasing elongation further. As the tensile properties alone does not depict the forming behaviour of cold rolled steel completely, plastic anisotropy ratio r, which is a good measure of deep drawability of steel, has been assessed. A mean value rm is defined as rm5(r0z2r45zr90)/4, where subscripts refer to the angles of tensile tests to the rolling direction. Figure 2 shows the effect of B/N ratio on rm for the steels (with and without boron) annealed with longer cycle. Steel with B/N ratio of 0?8 (steel C) shows lower value of rm (1?12) as compared to rm value of 1?66 in steel with B/N ratio of 0?3 (steel B2) processed under identical conditions of hot/cold rolling and annealing. The rm value of steel A, subjected to coiling temperature of 540uC and longer annealing cycle, has also been compared to steel B3 to assess the effect of boron. rm for both the steel were found to be nearly same (Fig. 2) with value of 1?76 for steel A and value of 1?74 for steel B3. The results show that lower value of B/N ratio does not affect rm adversely. It can be explained in terms of availability of nitrogen for AlN precipitation in steel during batch annealing. Depending on the Al, B and N concentration in steel, the range of temperature at which AlN and BN precipitate coincide in general. However, Ohmari and Yamanaka have reported that BN will form first compared to AlN due to higher diffusivity of boron. In the present study also, it appears that most of nitrogen has been combined by boron before precipitation of AlN in the hot rolled stage, which in turn has resulted in lower availability of nitrogen in solution depending on B/N atomic ratio for combining with aluminium during batch annealing. It is well known that there is strong influence of aluminium nitride during batch annealing of aluminium killed steel. High rm values are produced by textures containing a high proportion of grains with (111) planes and low proportion of (100) planes parallel to the sheet surface. The aluminium nitrides lead to enhancement of the (111) texture components and a concurrent reduction of the (100) components. While developing the desirable texture, aluminium nitrides also help at the same time in formation of a pancake grain structure which results in better rm value in steel. This emphasises the Research and Development Centre for Iron and Steel, Steel authority of India Limited, Ranchi, 834002, India